This invention relates in general to the construction of a heat absorber structure or heat exchanger particularly for plasma beam absorbers and thrust engines which includes a first wall which has a plurality of channels in an outer face thereof and a second wall which is electrodeposited on the first wall and overlies the channels and is provided with bulge areas at spaced locations along its length.
U.S. Pat. No. 3,595,025 and German Pat. No. 1,751,691 disclose rocket combustion chambers substantially comprising a basic structure or inner wall of a material which conducts heat well, particularly copper, with longitudinal cooling channels milled therein which are covered by an electroplated outer wall also of a well conducting material particularly copper. To obtain this structure, the milled channels are filled with an electrically conducting wax, whereupon the outer wall is deposited by electroplating and the wax is melted out.
During operation of the rocket, a cryogenic propellant component is conducted through the channels to remove the produced heat, so that the inner wall of the combustion chamber is intensely cooled and, at the same time, the propellant component is thermally conditioned or vaporized prior to being introduced into the head of the combustion chamber. Therefore, high thermal stresses are produced during operation of the rocket in the inner wall which is reinforced and stiffened by its web and therefore, in bond with the outer wall, has a high section modulus, thus is highly resistant to warping. While in rocket combustion chambers, what is wanted is to absorb and remove, substantially uniformly over the entire housing, a great amount of heat with a decreasing temperature gradient toward the thrust nozzle and a relatively cooler zone at the head of the combustion chamber where evaporative cooling prevails, the problem dealt with in the inventive solution is that the concerned heat absorbers are primarily exposed to local thermal loads. A plasma beam absorber, for example, has to endure extreme local beam shocks leading to great thermal expansions.